Imagine rolling over in bed at night, only to come face-to-face with your grandmother's demon-possessed corpse. She stares at you, unblinking. You know you're awake, but you don't know much beyond this. And all you can hear is a type of heavy breathing, which turns out to be your own.

Or, imagine a nine-foot monster appearing at the foot of your bed. As he begins to clamber onto your mattress, you leap up, full of adrenaline and beyond thought, only to run – literally collide – into a shadow who yells, "You're dreaming! You're dreaming!"

Once believed to be visits by the supernatural, researchers now view them as the result of an over-stimulated brain or as a sleep arousal disorder. They tend to afflict children between the ages of 3 and 12 – which can be frightening for parents as their child runs screaming hysterically through the house and is somehow unable to be 'brought back'.

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"Night terrors occur when children are only partly aroused from deep sleep so they are not quite awake, but they are not completely asleep either," says the Sydney Children's Hospital website.

"They tend to start within the first 2-3 hours after bedtime."

"Your child may remember being frightened, but without specific dream content and will not usually remember the night terror the next morning. Night terrors tend to occur in younger children and are usually outgrown by the end of primary-school age."

Unfortunately, this is only partly true for me. I almost always remember them, and I've never outgrown them.

I was 18 and living with my parents when my first one hit. I'd played netball earlier in the evening and instead of drinking water to hydrate myself, chugged down a couple of Diet Cokes. Idiotic, I know.

Still, even idiots find it alarming when they're awoken by their own screams.

Of course I don't know that I'm asleep. All I know is pure fear as I scream, yell and sprint from whichever demon is after me. In this sense, night terrors might be best described as waking nightmares. Or to put it another way, a nightmare you can't wake up from.

Although not all of mine have contained explicitly frightening creatures. Sometimes it's just a man, peering over me – which sounds harmless until it's 1am, his nose is half a centimetre away from my own and I have no idea I've been asleep.

'A nightmare you can't wake up from.' (Getty)

Once, when I was house-sharing in my early 20s, I woke up screaming after a vision of two demons in front of me. My poor flatmate froze in her own bed, resigned to the idea that whatever was harming me was coming for her next. We would laugh about it in the morning, and I would always promise to drink more water before bed. (That's one of the tips experts recommend, along with making sure your child is not too hot, and reading them a soothing story before sleep so they're calm. But again, this hasn't always worked for me.)

The worst was one night when I 'saw' a man leap up onto my balcony with a knife and run into my bathroom, taking someone who I believed to be my nephew with him and yelling, "You're next."

I was living alone at this stage so I don't know how many minutes passed before I realised it was a dream – I had a particularly difficult time trying to go back to sleep afterwards. After an hour of pacing and willing the atmosphere around me to neutralise, the way you do when a nightmare won't seem to leave, I gave up and watched TV until dawn.

Imagine my terror when I learned this the next day: that a man had murdered his sister in front of his nephew a block away from me that same night, and that police had not yet found him. He had used a knife.

I still can't explain it. And while it makes for a spooky story, I'll be happy if I never experience it again.

These days I don't scream anymore. Instead I'm usually awoken by my own voice, telling the dark and hideous creature that's decided to pay me a visit a firm "No". I can't explain this change either, as I'm not conscious, which means I can't take credit for it.

But I'd like to think it means that whatever it was in my brain that made me afraid has, through various nights of terror, somehow, somewhere along the line, made me brave.